Things are going exactly to plan for Atlanta’s defense. Two years ago, coach Dan Quinn and GM Thomas Dimitroff drafted defensive end Vic Beasley and corner Jalen Collins in the first two rounds. This year they took safety Keanu Neal in Round 1 and linebackers Deion Jones and De’Vondre Campbell in Rounds 2 and 4. All five of these players, plus unearthed gem Brian Poole (a rookie free-agent corner) will start in the base nickel in Sunday’s NFC Championship Game.

The youngsters, as expected, struggled early. But with playing time has come quick, significant improvement. Beasley led the NFL with 15.5 sacks this season. Collins and Poole have helped keep the secondary afloat after shutdown corner Desmond Trufant was lost to a pectoral injury in Week 9. Neal is blossoming into one of those Swiss Army Knife safeties. Jones and Campbell are playing faster and smarter in all phases, which has stabilized many of the personnel packages Quinn spent the first half of the season tinkering with.

De’Vondre Campbell and his fellow rookies have played faster and smarter as the season progressed.

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Not surprisingly, the Falcons defense as a whole has gotten better as the season progressed. Much better, in fact. After allowing 28.3 points a game in the 10 outings before their bye, they’ve given up 20.4 points an outing since. Their total takeaways are up from 11 to 13 and their passer rating allowed has gone from nearly 101 to under 78.

You can learn a lot about this defense from the story of exactly how it’s improved.

In the first half of the season, the Falcons’ biggest problem was that offenses attacked their rookies in Quinn’s foundational Cover 3 zone. A specific, but revealing, example was the deep diagonal crossing routes—a.k.a. “over” routes—that offenses ran out of trips sets. Three receivers would line up on the frontside. The receiver closest to the QB would sprint diagonally towards the backside. In Cover 3, the linebacker on that backside is responsible for this route. Almost always, it was Jones or Campbell, but sometimes it was Neal in this position. It didn’t matter; the rookies consistently got their eyes stuck on their underneath reads, forgetting the incoming receiver. And when they did identify the play, they usually weren’t able to run with the faster receiver.

Deep “over” routes weren’t the only way offenses attacked, but they shined the most glaring light on this defense’s shortcomings. But Atlanta’s response showed what quality coaching can do. Every coverage has weaknesses. One of Cover 3’s weaknesses is that linebackers can get matched against wide receivers inside. When this weakness is exposed, a defense can’t simply abandon its foundational coverage and go to something else—it must tweak that foundational coverage.

As the season wore on, Atlanta’s rookie ’backers and safety started playing with greater depth against trips formations. This created more space (and time) for them to react to the over routes. The added depth wasn’t a huge deal because Campbell, Neal and especially Jones have the speed to cover the additional ground. That’s a big reason Quinn and Dimitroff drafted them in the first place.

The change in alignment helped, but it couldn’t solve everything. There’s a fine line for Quinn to walk here. On the one hand, you want to stick to your core concepts and keep playing Cover 3. On the other, there are scenarios where it won’t matter how deep a linebacker or safety plays; if a wide receiver gets a clean release and is running top speed, the wide receiver will win. We saw this in Atlanta’s Week 8 matchup against Green Bay. On the opening series, the Packers spread out, put Jordy Nelson in the tight slot and ran him on an “over” route against Neal. It went for 58. The Packers continued to out-leverage Atlanta’s zone defense in ways like this until Quinn, late in the second quarter, shifted to more man coverage. After that, the game’s tenor changed, and the Falcons dictated the terms of engagement.

The speedy Deion Jones (right, 45) had an interception against the Seahawks.

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Shifting to man coverage is something Quinn wisely (and maybe humbly) has done more as the season has progressed. He’s realized that, with his Seahawks-style Cover 3 becoming more prominent around the NFL, offenses are finding ways to attack it that go beyond just “over” routes. Instead of adhering to the tough-guy “we’re going to do what wedo!” mentality that’s so often associated with football, Quinn adjusted, both in how he teaches Cover 3 and when he calls it. From this has come a significant expansion of the Falcons’ man coverage package. They employ a litany of concepts here, essentially making man-to-man their second foundation.

Give credit to Atlanta’s players, too. Man-to-man is inherently more of an execution defense. You wouldn’t have guessed Atlanta’s secondary could execute well enough without Trufant. At the time of his injury, no NFL corner was playing at a higher level. Trufant was the rare shutdown corner who could play any coverage outside and inside. Certainly it’s a more static secondary without him. Almost always, Collins is the outside corner, Poole the nickel slot. It’s easier for an offense to dictate matchups against them. But to both young corners’ immense credit, they’ve risen to the occasion. Collins, in fact, has made several big plays late in games after getting mercilessly picked on. Mental toughness.

Vic Beasley’s 15.5 sacks led the league, and there’s still room for improvement.

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On the subject of big plays, it’s critical you get these from your defensive line in a straightforward 4-3 man or zone scheme. This is Atlanta’s remaining question mark (or, for the optimists, their remaining wild card). Yes, Beasley had 15.5 sacks. But they often came in bunches because he’s still a somewhat scheme-dependent player. He’s fast and agile—and it shows when he’s afforded space. You’ll notice he either lines up extremely wide or serves as an exaggerated inside looper on stunts and twists. But when forced into confined areas, he still doesn’t quite have a refined repertoire of moves to call upon. Hopefully he’s watching and learning from 36-year-old Dwight Freeney.

Freeney can still flash as a rotational pass-rusher, but really Beasley is this front four’s only serious threat. Everyone else relies on effort and energy. That’s why you can expect the Falcons to take a pass-rusher early in next April’s draft. If that selection pans out like those of the last two years, this will soon be an upper-tier defense.

Quinn and Dimitroff should be thrilled. They’re working off a precise defensive blueprint and seeing things come together quickly. In fact, paired with an explosive offense, this defense could already be enough to bring home an NFC title. We’ll find out in four days.